GAZA CITY, GAZA
— Palestinian President Mahmoud Abbas's declaration over the weekend that he would hold an unprecedented referendum next month met monumental challenges Sunday when Hamas and Islamic Jihad soundly rejected plans for a popular vote.

They said that a prisoners' document that implied readiness to recognize Israel had been "misused" for political purposes.

The denunciation of Mr. Abbas's referendum plan comes amid spiraling violence in and around the Gaza Strip, with Israelis and Palestinians inflicting new fatalities and injuries on each other and raising the specter of a more heated conflict than the region has seen for several years.

Palestinians are expressing a mix of mourning and outrage after seven members of the same family were killed while enjoying a trip to the beach Friday, most probably by an Israeli army shell. Israel says the incident is under investigation and may not be the result of its own fire.

Two more Palestinians were killed in Israeli missile attacks early Sunday; Palestinians said they were Kassam rocket "activists" who had been martyred, while Israel said they were "terrorists." Also Sunday, a 60-year-old Israeli man was seriously wounded when one of the Kassam rockets, launched from the northern Gaza Strip, struck around Sderot.

The bloodshed provides a troubling backdrop to what is developing into a two-front battle.

Palestinians are facing a ratcheting up of a militant and increasingly mortal tit-for-tat with Israeli forces that has ballooned in the five months since the electoral rise of Hamas, the Islamic Resistance Movement.

And at home, Palestinians are increasingly facing off against themselves, as Hamas and like-minded Islamic groups are veering toward a path radically different from the one that President Abbas is trying lead his people down as he stakes his political career on Israeli-Palestinian reconciliation.

"We refuse these maneuvers totally, because these decisions are the right of all Palestinians all over the world, and they are not a matter for any referendum," Sami Abu Zuhri, a spokesman for the Hamas government.

"We reject the referendum and ask the president to reconsider," Mr. Abu Zuhri told a packed press conference here Sunday, in which Hamas teamed up with an erstwhile competitor, Islamic Jihad, to announce that prisoners affiliated with both movements were withdrawing their names from the so-called prisoners' document, issued last month.

Khaled al-Battesh, a spokesman for Islamic Jihad, read a statement from top prisoners from his organization and Hamas saying that they jailed activists were removing their names from the prisoner's document and were "committed to the decisions of our leaders outside the prison." The statement continued: "We consider the declaration of [Abbas's] referendum an abuse of our words. The document didn't go toward the purpose for which it was intended. It was for internal dialogue only."

The document had called for the establishment of a Palestinian state on the "lands of 1967," a reference to Gaza, the West Bank, and East Jerusalem, all of which Israel occupied in the Six- Day War. Many local and international observers saw in this document a watershed willingness - if only an implicit one - to recognize Israel. The document had been signed by Palestinian prisoners of all political stripes, and has been viewed by many as an inclination towards moderation.

Hamas, however, all but accused Abbas of usurping it to fit his needs. "This referendum is part of a plan to topple our government," Abu Zuhri said. "The referendum is something that is both illegal and dangerous, as it excludes about two-thirds of our people," he said, referring to Palestinian refugees living abroad.

"By saying '1967 land,' it was never meant to be recognizing Israel," he added. "To say that is like recognizing the occupation on our land of 1948. Internationally, this referendum would recognize the legitimacy of the occupation and give up our rights. Most dangerous, they want not just our leaders - as in the past - but for the whole Palestinian people to renounce its rights on the land of 1948."

Those statements may only frustrate the job of Abbas, who has been trying to run interference between the Hamas-led government and the international community, which has refused to continue funding the Palestinian Authority (PA) unless it meets major requirements: recognizing Israel and forgoing violence, such as Hamas's signature suicide bombings. After Friday's beach attack, Hamas said that its self-imposed cease-fire was now off, and warned Israelis over the weekend to expect attacks.

At the Ghaliya home in Beit Lahiya, in the northern Gaza region that has become a regular hotbed of Israeli-Palestinian arms volleys, family members sat in the mourning tent, listened to Hamas-led prayers and grieved. Nearby, a truck blasting the names of the new "Hamas martyrs" called on people to attend their funerals and accompanying protest marches later that day.

Ayham Ghaliya lost his parents and siblings in the beach explosion. They had been simply farmers enjoying their day off. He said he could never support Abbas's referendum now. "Just recently, people exercised democratic processes and elected Hamas, and a referendum might create fitna," he says, using a Islamic term for turning brother against brother, "and this would lead to civil war. I don't think I will vote for it."

Others, thinking about lost relatives and neighbors, couldn't think politics - nor see into the end of July, when Abbas set his referendum date. "My relatives work so hard and they went to the beach to have a good time," says Rima Ghaliya, a cousin. "It's a shame, what they're doing to innocent children. If they want to hurt someone, why not go after the people who launch the Kassams?"